Financial transaction cards, e.g., credit cards, debit cards, gift cards, or store cards, are used in many commercial transactions. For example, a store can use a point-of-sale (POS) system to process financial transaction card transactions of the store's customers. The financial transaction card can have a magnetic stripe attached to one face of the card. Account information, e.g., a card number, an expiration date, or a cardholder name, can be encoded in one or more data tracks on the magnetic stripe as magnetic particles having various orientations. In a transaction, a customer swipes a financial transaction card in a card reader of the POS system. The card reader includes a read head for reading the encoded account information. During a card swipe, the magnetic stripe moves across the read head. The read head detects the magnetic fields generated by the particles. The card reader then reproduces the account information based on variations the detected magnetic fields.
The card reader usually has a slot to guide the financial transaction card to move in a straight line across the read head. If the card swipe is not straight enough, the read head may be aligned with a wrong track, or with no track at all. The misalignment can cause a card read error. The customer will then re-swipe the card.
Like reference symbols in the various drawings indicate like elements.